feature: add gpu node autoscaling support for all modules (terraform-…

…google-modules#807)

* updater example/node_pool cluster_autoscaling var to work with
  gpu_resources

examples/node_pool/variables.tf

@@ -60,6 +60,11 @@ variable "cluster_autoscaling" {
     max_cpu_cores       = number
     min_memory_gb       = number
     max_memory_gb       = number
+    gpu_resources       = list(object({
+      resource_type = string
+      minimum       = number
+      maximum       = number
+    }))
   })
   default = {
     enabled             = false
@@ -68,6 +73,7 @@ variable "cluster_autoscaling" {
     min_cpu_cores       = 0
     max_memory_gb       = 0
     min_memory_gb       = 0
+    gpu_resources       = []
   }
   description = "Cluster autoscaling configuration. See [more details](https://cloud.google.com/kubernetes-engine/docs/reference/rest/v1beta1/projects.locations.clusters#clusterautoscaling)"
 }